Array out-of-bounds reference in xLAQR5.

Bug report and fix from Mathew Cross (NAG) on Sat Aug 14 2010:

In the section of the code "Special case: 2-by-2 reflection (if needed)" the logical test
IF( BMP22 .AND. ( V( 1, M22 ).NE.ZERO ) )
must be split into a nested test
IF (BMP22) THEN, IF (V(1,M22).NE.ZERO) THEN...
If .NOT. BMP22 then M22 can exceed the second extent of V (and recall that logical expressions can be evaluated in any order in Fortran).

See http://icl.cs.utk.edu/lapack-forum/viewtopic.php?f=2&t=1949.

diff --git a/SRC/claqr5.f b/SRC/claqr5.f
index c7b00f7d55021b91d72607dd433e95bac841f56c..9395c1ea802d0c7c4ca1d4362c9d42999bf1cd51 100644 (file)
--- a/SRC/claqr5.f
+++ b/SRC/claqr5.f
@@ -441,32 +441,34 @@
 *           ==== Special case: 2-by-2 reflection (if needed) ====
 *
             K = KRCOL + 3*( M22-1 )
-            IF( BMP22 .AND. ( V( 1, M22 ).NE.ZERO ) ) THEN
-               DO 90 J = JTOP, MIN( KBOT, K+3 )
-                  REFSUM = V( 1, M22 )*( H( J, K+1 )+V( 2, M22 )*
-     $                     H( J, K+2 ) )
-                  H( J, K+1 ) = H( J, K+1 ) - REFSUM
-                  H( J, K+2 ) = H( J, K+2 ) -
-     $                          REFSUM*CONJG( V( 2, M22 ) )
-   90          CONTINUE
-*
-               IF( ACCUM ) THEN
-                  KMS = K - INCOL
-                  DO 100 J = MAX( 1, KTOP-INCOL ), KDU
-                     REFSUM = V( 1, M22 )*( U( J, KMS+1 )+V( 2, M22 )*
-     $                        U( J, KMS+2 ) )
-                     U( J, KMS+1 ) = U( J, KMS+1 ) - REFSUM
-                     U( J, KMS+2 ) = U( J, KMS+2 ) -
-     $                               REFSUM*CONJG( V( 2, M22 ) )
-  100             CONTINUE
-               ELSE IF( WANTZ ) THEN
-                  DO 110 J = ILOZ, IHIZ
-                     REFSUM = V( 1, M22 )*( Z( J, K+1 )+V( 2, M22 )*
-     $                        Z( J, K+2 ) )
-                     Z( J, K+1 ) = Z( J, K+1 ) - REFSUM
-                     Z( J, K+2 ) = Z( J, K+2 ) -
+            IF( BMP22 ) THEN
+               IF ( V( 1, M22 ).NE.ZERO ) THEN
+                  DO 90 J = JTOP, MIN( KBOT, K+3 )
+                     REFSUM = V( 1, M22 )*( H( J, K+1 )+V( 2, M22 )*
+     $                        H( J, K+2 ) )
+                     H( J, K+1 ) = H( J, K+1 ) - REFSUM
+                     H( J, K+2 ) = H( J, K+2 ) -
      $                             REFSUM*CONJG( V( 2, M22 ) )
-  110             CONTINUE
+   90             CONTINUE
+*
+                  IF( ACCUM ) THEN
+                     KMS = K - INCOL
+                     DO 100 J = MAX( 1, KTOP-INCOL ), KDU
+                        REFSUM = V( 1, M22 )*( U( J, KMS+1 )+
+     $                           V( 2, M22 )*U( J, KMS+2 ) )
+                        U( J, KMS+1 ) = U( J, KMS+1 ) - REFSUM
+                        U( J, KMS+2 ) = U( J, KMS+2 ) -
+     $                                  REFSUM*CONJG( V( 2, M22 ) )
+  100                CONTINUE
+                  ELSE IF( WANTZ ) THEN
+                     DO 110 J = ILOZ, IHIZ
+                        REFSUM = V( 1, M22 )*( Z( J, K+1 )+V( 2, M22 )*
+     $                           Z( J, K+2 ) )
+                        Z( J, K+1 ) = Z( J, K+1 ) - REFSUM
+                        Z( J, K+2 ) = Z( J, K+2 ) -
+     $                                REFSUM*CONJG( V( 2, M22 ) )
+  110                CONTINUE
+                  END IF
                END IF
             END IF
 *

diff --git a/SRC/dlaqr5.f b/SRC/dlaqr5.f
index 3e57eb05a0eeadeacb31864f12bf0c24f11a8b5c..7779de02f114d8d56ef014173323b0e9cd694514 100644 (file)
--- a/SRC/dlaqr5.f
+++ b/SRC/dlaqr5.f
@@ -453,29 +453,32 @@
 *           ==== Special case: 2-by-2 reflection (if needed) ====
 *
             K = KRCOL + 3*( M22-1 )
-            IF( BMP22 .AND. ( V( 1, M22 ).NE.ZERO ) ) THEN
-               DO 100 J = JTOP, MIN( KBOT, K+3 )
-                  REFSUM = V( 1, M22 )*( H( J, K+1 )+V( 2, M22 )*
-     $                     H( J, K+2 ) )
-                  H( J, K+1 ) = H( J, K+1 ) - REFSUM
-                  H( J, K+2 ) = H( J, K+2 ) - REFSUM*V( 2, M22 )
-  100          CONTINUE
-*
-               IF( ACCUM ) THEN
-                  KMS = K - INCOL
-                  DO 110 J = MAX( 1, KTOP-INCOL ), KDU
-                     REFSUM = V( 1, M22 )*( U( J, KMS+1 )+V( 2, M22 )*
-     $                        U( J, KMS+2 ) )
-                     U( J, KMS+1 ) = U( J, KMS+1 ) - REFSUM
-                     U( J, KMS+2 ) = U( J, KMS+2 ) - REFSUM*V( 2, M22 )
+            IF( BMP22 ) THEN
+               IF ( V( 1, M22 ).NE.ZERO ) THEN
+                  DO 100 J = JTOP, MIN( KBOT, K+3 )
+                     REFSUM = V( 1, M22 )*( H( J, K+1 )+V( 2, M22 )*
+     $                        H( J, K+2 ) )
+                     H( J, K+1 ) = H( J, K+1 ) - REFSUM
+                     H( J, K+2 ) = H( J, K+2 ) - REFSUM*V( 2, M22 )
+  100             CONTINUE
+*
+                  IF( ACCUM ) THEN
+                     KMS = K - INCOL
+                     DO 110 J = MAX( 1, KTOP-INCOL ), KDU
+                        REFSUM = V( 1, M22 )*( U( J, KMS+1 )+
+     $                           V( 2, M22 )*U( J, KMS+2 ) )
+                        U( J, KMS+1 ) = U( J, KMS+1 ) - REFSUM
+                        U( J, KMS+2 ) = U( J, KMS+2 ) -
+     $                                  REFSUM*V( 2, M22 )
   110             CONTINUE
-               ELSE IF( WANTZ ) THEN
-                  DO 120 J = ILOZ, IHIZ
-                     REFSUM = V( 1, M22 )*( Z( J, K+1 )+V( 2, M22 )*
-     $                        Z( J, K+2 ) )
-                     Z( J, K+1 ) = Z( J, K+1 ) - REFSUM
-                     Z( J, K+2 ) = Z( J, K+2 ) - REFSUM*V( 2, M22 )
-  120             CONTINUE
+                  ELSE IF( WANTZ ) THEN
+                     DO 120 J = ILOZ, IHIZ
+                        REFSUM = V( 1, M22 )*( Z( J, K+1 )+V( 2, M22 )*
+     $                           Z( J, K+2 ) )
+                        Z( J, K+1 ) = Z( J, K+1 ) - REFSUM
+                        Z( J, K+2 ) = Z( J, K+2 ) - REFSUM*V( 2, M22 )
+  120                CONTINUE
+                  END IF
                END IF
             END IF
 *

diff --git a/SRC/slaqr5.f b/SRC/slaqr5.f
index 83a2b2fce0d598610ecef0e663267d76737c1243..9ad0d51bc8117c9dcf35976ebe98d3b894fb87d4 100644 (file)
--- a/SRC/slaqr5.f
+++ b/SRC/slaqr5.f
@@ -453,29 +453,32 @@
 *           ==== Special case: 2-by-2 reflection (if needed) ====
 *
             K = KRCOL + 3*( M22-1 )
-            IF( BMP22 .AND. ( V( 1, M22 ).NE.ZERO ) ) THEN
-               DO 100 J = JTOP, MIN( KBOT, K+3 )
-                  REFSUM = V( 1, M22 )*( H( J, K+1 )+V( 2, M22 )*
-     $                     H( J, K+2 ) )
-                  H( J, K+1 ) = H( J, K+1 ) - REFSUM
-                  H( J, K+2 ) = H( J, K+2 ) - REFSUM*V( 2, M22 )
-  100          CONTINUE
-*
-               IF( ACCUM ) THEN
-                  KMS = K - INCOL
-                  DO 110 J = MAX( 1, KTOP-INCOL ), KDU
-                     REFSUM = V( 1, M22 )*( U( J, KMS+1 )+V( 2, M22 )*
-     $                        U( J, KMS+2 ) )
-                     U( J, KMS+1 ) = U( J, KMS+1 ) - REFSUM
-                     U( J, KMS+2 ) = U( J, KMS+2 ) - REFSUM*V( 2, M22 )
-  110             CONTINUE
-               ELSE IF( WANTZ ) THEN
-                  DO 120 J = ILOZ, IHIZ
-                     REFSUM = V( 1, M22 )*( Z( J, K+1 )+V( 2, M22 )*
-     $                        Z( J, K+2 ) )
-                     Z( J, K+1 ) = Z( J, K+1 ) - REFSUM
-                     Z( J, K+2 ) = Z( J, K+2 ) - REFSUM*V( 2, M22 )
-  120             CONTINUE
+            IF( BMP22 ) THEN
+               IF ( V( 1, M22 ).NE.ZERO ) THEN
+                  DO 100 J = JTOP, MIN( KBOT, K+3 )
+                     REFSUM = V( 1, M22 )*( H( J, K+1 )+V( 2, M22 )*
+     $                        H( J, K+2 ) )
+                     H( J, K+1 ) = H( J, K+1 ) - REFSUM
+                     H( J, K+2 ) = H( J, K+2 ) - REFSUM*V( 2, M22 )
+  100             CONTINUE
+*
+                  IF( ACCUM ) THEN
+                     KMS = K - INCOL
+                     DO 110 J = MAX( 1, KTOP-INCOL ), KDU
+                        REFSUM = V( 1, M22 )*( U( J, KMS+1 )+
+     $                           V( 2, M22 )*U( J, KMS+2 ) )
+                        U( J, KMS+1 ) = U( J, KMS+1 ) - REFSUM
+                        U( J, KMS+2 ) = U( J, KMS+2 ) - REFSUM*
+     $                                  V( 2, M22 )
+  110                CONTINUE
+                  ELSE IF( WANTZ ) THEN
+                     DO 120 J = ILOZ, IHIZ
+                        REFSUM = V( 1, M22 )*( Z( J, K+1 )+V( 2, M22 )*
+     $                           Z( J, K+2 ) )
+                        Z( J, K+1 ) = Z( J, K+1 ) - REFSUM
+                        Z( J, K+2 ) = Z( J, K+2 ) - REFSUM*V( 2, M22 )
+  120                CONTINUE
+                  END IF
                END IF
             END IF
 *

diff --git a/SRC/zlaqr5.f b/SRC/zlaqr5.f
index d112531f292c9f46e5f09b3804b4c87ad1cd6865..56bc028d44fc9f2c01ed87a85294405be1fb9752 100644 (file)
--- a/SRC/zlaqr5.f
+++ b/SRC/zlaqr5.f
@@ -441,32 +441,34 @@
 *           ==== Special case: 2-by-2 reflection (if needed) ====
 *
             K = KRCOL + 3*( M22-1 )
-            IF( BMP22 .AND. ( V( 1, M22 ).NE.ZERO ) ) THEN
-               DO 90 J = JTOP, MIN( KBOT, K+3 )
-                  REFSUM = V( 1, M22 )*( H( J, K+1 )+V( 2, M22 )*
-     $                     H( J, K+2 ) )
-                  H( J, K+1 ) = H( J, K+1 ) - REFSUM
-                  H( J, K+2 ) = H( J, K+2 ) -
-     $                          REFSUM*DCONJG( V( 2, M22 ) )
-   90          CONTINUE
-*
-               IF( ACCUM ) THEN
-                  KMS = K - INCOL
-                  DO 100 J = MAX( 1, KTOP-INCOL ), KDU
-                     REFSUM = V( 1, M22 )*( U( J, KMS+1 )+V( 2, M22 )*
-     $                        U( J, KMS+2 ) )
-                     U( J, KMS+1 ) = U( J, KMS+1 ) - REFSUM
-                     U( J, KMS+2 ) = U( J, KMS+2 ) -
-     $                               REFSUM*DCONJG( V( 2, M22 ) )
-  100             CONTINUE
-               ELSE IF( WANTZ ) THEN
-                  DO 110 J = ILOZ, IHIZ
-                     REFSUM = V( 1, M22 )*( Z( J, K+1 )+V( 2, M22 )*
-     $                        Z( J, K+2 ) )
-                     Z( J, K+1 ) = Z( J, K+1 ) - REFSUM
-                     Z( J, K+2 ) = Z( J, K+2 ) -
+            IF( BMP22 ) THEN
+               IF ( V( 1, M22 ).NE.ZERO ) THEN
+                  DO 90 J = JTOP, MIN( KBOT, K+3 )
+                     REFSUM = V( 1, M22 )*( H( J, K+1 )+V( 2, M22 )*
+     $                        H( J, K+2 ) )
+                     H( J, K+1 ) = H( J, K+1 ) - REFSUM
+                     H( J, K+2 ) = H( J, K+2 ) -
      $                             REFSUM*DCONJG( V( 2, M22 ) )
-  110             CONTINUE
+   90             CONTINUE
+*
+                  IF( ACCUM ) THEN
+                     KMS = K - INCOL
+                     DO 100 J = MAX( 1, KTOP-INCOL ), KDU
+                        REFSUM = V( 1, M22 )*( U( J, KMS+1 )+
+     $                           V( 2, M22 )*U( J, KMS+2 ) )
+                        U( J, KMS+1 ) = U( J, KMS+1 ) - REFSUM
+                        U( J, KMS+2 ) = U( J, KMS+2 ) -
+     $                                  REFSUM*DCONJG( V( 2, M22 ) )
+  100                CONTINUE
+                  ELSE IF( WANTZ ) THEN
+                     DO 110 J = ILOZ, IHIZ
+                        REFSUM = V( 1, M22 )*( Z( J, K+1 )+V( 2, M22 )*
+     $                           Z( J, K+2 ) )
+                        Z( J, K+1 ) = Z( J, K+1 ) - REFSUM
+                        Z( J, K+2 ) = Z( J, K+2 ) -
+     $                                REFSUM*DCONJG( V( 2, M22 ) )
+  110                CONTINUE
+                  END IF
                END IF
             END IF
 *